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A related concern would be surfacing the "online" part as explicit resources and actions for the user instead of implicit, background magic. If you are sufficie

A related concern would be surfacing the "online" part as explicit resources and actions for the user instead of implicit, background magic. If you are sufficiently offline in your lifestyle, you need to plan your communication phases. I recently got into using a GPS sports watch. It is the kind of thing I would want to use in an offline fashion, i.e. go somewhere off the grid and track my hikes or bike rides. These devices are designed to function offline for a stretch of time, but they have a requirement to eventually sync to an online system. They will eventually fill up with recorded sensor data and you want to offload that somewhere else before clearing local device storage. More importantly, satellite positioning receivers need a cached "ephemeris" file that helps them predict which satellites will be overhead at a given time to operate efficiently, accurately, and quickly. Unfortunately, the manufacturers have been infected with smartwatch expectations. They started designing it as if it is always online, and the syncing functions are implicit background behaviors. When doing sporadic syncs and going back offline, it is hard to influence it to "get latest ephemeris" when you known you have internet connectivity and will be going offline again. Worse, these results are localized and it implicitly gets ephemeris for its current location. The UI doesn't allow you to indicate a destination and pre-load the right data to allow fully offline function on arrival.

deceptionatd 4y ago
> More importantly, satellite positioning receivers need a cached "ephemeris" file that helps them predict which satellites will be overhead at a given time to operate efficiently, accurately, and quickly. Interesting, I've never heard of that particular optimization for GNSS before. I know GPS transmits ephemeris information in each frame, since that's the input data for the positioning calculations. I've got a number of Garmin watches, and they've always been able to get a position fix even after being disconnected for weeks. I find GNSS implementations very interesting, which manufacturer is making their watches like this?
- saltcured 4y ago
  Garmin watches do! Go into the System -> About menu and there is a page showing ephemeris status. Their documentation states that this may expire after approximately 30 days or if you travel more than 200 miles, while it will update during syncing. I've seen it expire in less than two weeks with daily use of GPS but phone syncing disabled. It will still get position, but it can be the difference between an almost immediate fix after opening an activity menu or a delay for tens of seconds to minutes. Distance and pace measurements also seem to be lower quality when operating without a current ephemeris file.

deceptionatd 4y ago

> More importantly, satellite positioning receivers need a cached "ephemeris" file that helps them predict which satellites will be overhead at a given time to operate efficiently, accurately, and quickly. Interesting, I've never heard of that particular optimization for GNSS before. I know GPS transmits ephemeris information in each frame, since that's the input data for the positioning calculations. I've got a number of Garmin watches, and they've always been able to get a position fix even after being disconnected for weeks. I find GNSS implementations very interesting, which manufacturer is making their watches like this?

saltcured 4y ago
Garmin watches do! Go into the System -> About menu and there is a page showing ephemeris status. Their documentation states that this may expire after approximately 30 days or if you travel more than 200 miles, while it will update during syncing. I've seen it expire in less than two weeks with daily use of GPS but phone syncing disabled. It will still get position, but it can be the difference between an almost immediate fix after opening an activity menu or a delay for tens of seconds to minutes. Distance and pace measurements also seem to be lower quality when operating without a current ephemeris file.